Any asphaltic based flat roofing material will bind properly with a good grade Plastic Roofing Cement.
If there is No Boot flashing on it now, why did you describe the Lead covering in your first post?
I think possibly you Do have a lead boot flashings, but that does not matter for the repair aspect.
Get a new pipe boot flashing. Remove the old one carefully, so as not to damage the roofing material it is bonded to.
Install the new one. Under the flanges, trowel apply a thin layer of plastic roofing cement. Set the new boots flanges into this roofing cement. (Use some chalk to outline the perimeter edges of the boot flashing first, so you do not go overboard and get the area all messy. Tap the flanges into the bed of roofing cement. Now, apply the layer or roof cement, membrane fabric and then a top skin coat of roofing cement as described in the other posts I pointed out to you in my other reply.